Constraining the Temporal History of Fault Slip Through the Integration of Seismic Reflection Data and Radiocarbon-Dated Sediment Cores
James Muirhead, Syracuse University
Christopher Scholz, Syracuse University
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Constraining how faulting is distributed in both time and space is challenging, often requiring paleoseismic trenching that can be expensive and potentially environmentally hazardous. However, where faults and fault systems intersect water bodies (rivers and lakes), these structures can be precisely resolved through relatively low-cost geophysical methods. Combining these data with targeted radiocarbon dating of key seismic horizons provides constraints on fault slip histories for large fault populations, which can be applied to both tectonic and paleoseismic analyses. We utilized over 1100 km of high-resolution Compressed High Intensity Radar Pulse (CHIRP) 2D seismic reflection data, integrated with a suite of radiocarbon-dated sediment cores (3 in total), to constrain a ~10,000 year history of fault activity in south Lake Turkana, Kenya. Here, a set of ~N-S-striking intra-rift faults exhibit time-averaged slip rates as high as 2.5 mm/yr, with the highest slip rates occurring along faults within ~10 km of the rift axis. These data are used to better understand seismic hazards in the region, controls rift basin development, and also how tectonic activity may be affected by climate-induced lake level changes. Similar techniques may be applied to normal faults and fault populations in faulted lake systems in western North America.